'\" et
.TH TEMPNAM "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
tempnam
\(em create a name for a temporary file
.SH SYNOPSIS
.LP
.nf
#include <stdio.h>
.P
char *tempnam(const char *\fIdir\fP, const char *\fIpfx\fP);
.fi
.SH DESCRIPTION
The
\fItempnam\fR()
function shall generate a pathname that may be used for a temporary
file.
.P
The
\fItempnam\fR()
function allows the user to control the choice of a directory. The
.IR dir
argument points to the name of the directory in which the file is to be
created. If
.IR dir
is a null pointer or points to a string which is not a name for an
appropriate directory, the path prefix defined as P_tmpdir in the
.IR <stdio.h> 
header shall be used. If that directory is not accessible, an
implementation-defined directory may be used.
.P
Many applications prefer their temporary files to have certain initial
letter sequences in their names. The
.IR pfx
argument should be used for this. This argument may be a null pointer
or point to a string of up to five bytes to be used as the beginning of
the filename.
.P
Some implementations of
\fItempnam\fR()
may use
\fItmpnam\fR()
internally. On such implementations, if called more than
{TMP_MAX}
times in a single process, the behavior is implementation-defined.
.SH "RETURN VALUE"
Upon successful completion,
\fItempnam\fR()
shall allocate space for a string, put the generated pathname in that
space, and return a pointer to it. The pointer shall be suitable for
use in a subsequent call to
\fIfree\fR().
Otherwise, it shall return a null pointer and set
.IR errno
to indicate the error.
.SH ERRORS
The
\fItempnam\fR()
function shall fail if:
.TP
.BR ENOMEM
Insufficient storage space is available.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
.SS "Generating a Pathname"
.P
The following example generates a pathname for a temporary file in
directory
.BR /tmp ,
with the prefix
.IR file .
After the pathname has been created, the call to
\fIfree\fR()
deallocates the space used to store the pathname.
.sp
.RS 4
.nf

#include <stdio.h>
#include <stdlib.h>
\&...
const char *directory = "/tmp";
const char *fileprefix = "file";
char *file;
.P
file = tempnam(directory, fileprefix);
free(file);
.fi
.P
.RE
.SH "APPLICATION USAGE"
This function only creates pathnames. It is the application's
responsibility to create and remove the files. Between the time a
pathname is created and the file is opened, it is possible for some
other process to create a file with the same name. Applications may
find
\fItmpfile\fR()
more useful.
.P
Applications should use the
\fItmpfile\fR(),
\fImkdtemp\fR(),
or
\fImkstemp\fR()
functions instead of the obsolescent
\fItempnam\fR()
function.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
The
\fItempnam\fR()
function may be removed in a future version.
.SH "SEE ALSO"
.IR "\fIfopen\fR\^(\|)",
.IR "\fIfree\fR\^(\|)",
.IR "\fImkdtemp\fR\^(\|)",
.IR "\fIopen\fR\^(\|)",
.IR "\fItmpfile\fR\^(\|)",
.IR "\fItmpnam\fR\^(\|)",
.IR "\fIunlink\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<stdio.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
